Breath condensate ammonium is lower in children with chronic asthma.

Exhaled breath condensate pH and ammonium reflect asthmatic status and acute exacerbations in adults. The aim of this study was to assess whether pH and ammonium could reflect asthma and its severity in children. The current study comprised two parts: 1) a cross-section of 74 children with asthma (median age 10.5 yrs) compared with 47 healthy controls (median age 10 yrs); and 2) longitudinal assessment of eight children (mean age 8.5 yrs) admitted with asthma exacerbation. Condensate pH and ammonium were compared with clinical observations. In the cross-sectional part of the study, lower per cent forced expiratory volume in one second was associated with more symptoms and treatment. There was no significant difference between median pH in children with stable asthma (6.05) compared with controls (5.90). Ammonium was significantly lower in children with asthma (median 258 microM) compared with controls (median 428 microM). No association was found between ammonium or pH and lung function or symptom-free days. In the longitudinal study, significant improvements in oxygen saturation and respiratory rate with treatment of an acute exacerbation were not reflected by changes in pH or ammonium. In conclusion, pH does not appear to reflect disease or severity in children with asthma. Ammonium was significantly lower in children with asthma when compared with controls.